New, more stringent emission limits for diesel engines necessitate the use of exhaust after-treatment devices, such as diesel particulate filters. Certain after-treatment devices include a regeneration cycle. During the regeneration cycle, the temperature of the exhaust gas plume may rise significantly above acceptable temperatures normally experienced by exhaust systems without such after-treatment devices. As an example, exhaust systems without after-treatment devices typically discharge exhaust gas at a temperature of around 650 degrees Kelvin. An exhaust system having an after-treatment device that includes a regeneration cycle may experience an exhaust gas plume temperature exceeding 900 degrees Kelvin at its center core. Exhaust gas at this high exit temperature creates a potentially hazardous operating environment.
Prior art and current exhaust pipe diffusers are not designed to optimally intermingle cooling air with a hot core stream in the center of the exhaust pipe, as described above. The result at the exit plane can be a cool ring of exhaust flow surrounding a very hot exhaust core.
Thus, there exists a need for a flow diffuser for an exhaust pipe for diffusing hot exhaust gas on exit from an exhaust pipe.